An apparatus for controlling operating characteristic quantities of an internal combustion engine to optimal values is known from, U.S. Pat. No. 4,487,186. In this apparatus, engine variables such as the metering of the air-fuel mixture or the ignition timing are anticipatorily controlled and varied to selectable times wherein the corresponding reaction of the internal combustion engine to these variations serves to determine optimal power, for example, or the minimal, specific fuel consumption. This known apparatus therefore includes an anticipatory control of the fuel metering, for example, with a superposed control which corrects unavoidable errors in the measurement of anticipatory control values.
An anticipatory control of the mixture as accurate as possible in dependence upon, for example, the engine speed n and the throttle flap position .alpha. is necessary to hold transients of control as small as possible. To prevent this disadvantage of a very exact adjustment of the anticipatory control values, it has already been known for a long time to utilize "learning characteristic fields". In this connection, the characteristic field values are stored in a memory and, when the internal combustion engine is started, these values are transferred into a write-read memory. Subsequent thereto, individual characteristic field values or characteristic field regions are corrected in dependence upon operating characteristic quantities and written into the memory.
In practice, it has been shown that this characteristic field learning process does not exhibit an optimal effect under all operating conditions of the internal combustion engine. Especially with known apparatus and methods, it has not been possible to hold exhaust gas emissions low while at the same time having a minimal consumption of fuel for the peripheral condition of a satisfactory driving behavior in all operating conditions.